Provides iteration through tokens of a given string:
- fFullStr stores the string to be split. It is never modified.
- fSplitRe is the perl-re that is used to separete the tokens.
- fReturnVoid if true, empty strings will be returned.
Current token is stored in the TString base-class.
During construction no match is done, use NextToken() to get the first
and all subsequent tokens.